Pulmonary Function Testing (PFT)

Pulmonary Function Tests (PFT) are a group of tests that check how well your lungs are working. These tests measure your lung capacity (how much air your lungs hold), how quickly you inhale (breathe air in), and how quickly you exhale (breathe air out). They also look at how much oxygen you inhale and how much carbon dioxide you exhale.

When are PFTs used in cancer care?

If you are going to have surgery for lung cancer, you may have PFTs to make sure your lungs are healthy enough for surgery. They might also be done throughout your cancer treatment to check if your lung function has changed.

What are the types of PFTs?

• Spirometry: This is the most common PFT test. This test measures how quickly air leaves your lungs and the amount of air that you exhale.
  • During a spirometry test, your provider measures Forced Expiratory Volume in 1 second (FEV1), which is the amount of air you breathe out in 1 second. Your provider will also measure Forced Vital Capacity (FVC), which is the total amount of air that you breathe out. These results give your ratio of FEV1 to FVC, which helps measure how healthy your lungs are.
• Lung Volume Test: This test helps your provider measure how much air your lungs can hold.
  • One way of doing a lung volume test is by using a method called body plethysmography. A plethysmograph is an airtight chamber that you go into, and body plethysmography is done by using a type of spirometer to check how much air your lungs hold.
• Lung Diffusion Capacity Test: This test looks at how well you absorb (take in) air. To do this test, you breathe in a gas that has a small amount of carbon monoxide in it. Then, it is measured how well the gas goes from your lungs to your blood. 
• Cadiopulmonary Exercise Test: This type of test checks how well your lungs work and how much oxygen your body needs while you are active.
• Oscillometry: This test helps your provider see how open your airways are and check how air moves through your lungs.

In some cases, you might have one, a few, or all of these tests. Tell your provider if you feel lightheaded or dizzy during or after the tests.

How do I prepare for a PFT?

Your provider will tell you if there are specific things you need to do before having a PFT. In some cases, your provider may tell you not to eat a large meal before the test. Your provider will tell you if you need to stop taking any medications before the test. If you smoke, do not smoke for at least 6 hours before the test.

Ask your provider if you have any questions or concerns about PFTs.